WO2000079018A1 - Sputtering method using virtual shutter - Google Patents
Sputtering method using virtual shutter Download PDFInfo
- Publication number
- WO2000079018A1 WO2000079018A1 PCT/US2000/015715 US0015715W WO0079018A1 WO 2000079018 A1 WO2000079018 A1 WO 2000079018A1 US 0015715 W US0015715 W US 0015715W WO 0079018 A1 WO0079018 A1 WO 0079018A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- sputtering
- wafer
- chamber
- plasma
- cathode
- Prior art date
Links
- 238000004544 sputter deposition Methods 0.000 title claims abstract description 164
- 239000007789 gas Substances 0.000 claims abstract description 140
- 238000000034 method Methods 0.000 claims abstract description 122
- 239000000758 substrate Substances 0.000 claims abstract description 95
- 230000008569 process Effects 0.000 claims abstract description 71
- 238000005240 physical vapour deposition Methods 0.000 claims abstract description 54
- 238000012545 processing Methods 0.000 claims abstract description 51
- 229910001218 Gallium arsenide Inorganic materials 0.000 claims abstract description 40
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 claims abstract description 33
- 229910052724 xenon Inorganic materials 0.000 claims abstract description 8
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052743 krypton Inorganic materials 0.000 claims abstract description 5
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 claims abstract description 4
- 235000012431 wafers Nutrition 0.000 claims description 101
- 239000000463 material Substances 0.000 claims description 89
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 26
- 238000000151 deposition Methods 0.000 claims description 23
- 238000005477 sputtering target Methods 0.000 claims description 17
- 229910052786 argon Inorganic materials 0.000 claims description 16
- 238000001755 magnetron sputter deposition Methods 0.000 claims description 14
- 230000003247 decreasing effect Effects 0.000 claims description 10
- 229910052751 metal Inorganic materials 0.000 claims description 8
- 239000002184 metal Substances 0.000 claims description 8
- 230000000670 limiting effect Effects 0.000 claims description 6
- 238000007789 sealing Methods 0.000 claims 6
- -1 argon ions Chemical class 0.000 claims 4
- 239000002245 particle Substances 0.000 abstract description 12
- 239000000203 mixture Substances 0.000 abstract description 5
- 239000010936 titanium Substances 0.000 description 21
- 230000008859 change Effects 0.000 description 18
- 230000008021 deposition Effects 0.000 description 13
- 230000003750 conditioning effect Effects 0.000 description 11
- 150000002500 ions Chemical class 0.000 description 10
- 230000000694 effects Effects 0.000 description 9
- 230000007423 decrease Effects 0.000 description 8
- 229910052719 titanium Inorganic materials 0.000 description 8
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 7
- 239000003870 refractory metal Substances 0.000 description 7
- 238000000576 coating method Methods 0.000 description 4
- MAKDTFFYCIMFQP-UHFFFAOYSA-N titanium tungsten Chemical compound [Ti].[W] MAKDTFFYCIMFQP-UHFFFAOYSA-N 0.000 description 4
- 229910052581 Si3N4 Inorganic materials 0.000 description 3
- 238000011109 contamination Methods 0.000 description 3
- 238000005137 deposition process Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000007935 neutral effect Effects 0.000 description 3
- 229910052756 noble gas Inorganic materials 0.000 description 3
- 150000002835 noble gases Chemical class 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- 238000001020 plasma etching Methods 0.000 description 3
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 239000007943 implant Substances 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 230000003278 mimic effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003449 preventive effect Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- XMPZLAQHPIBDSO-UHFFFAOYSA-N argon dimer Chemical compound [Ar].[Ar] XMPZLAQHPIBDSO-UHFFFAOYSA-N 0.000 description 1
- DGJPLFUDZQEBFH-UHFFFAOYSA-N argon xenon Chemical compound [Ar].[Xe] DGJPLFUDZQEBFH-UHFFFAOYSA-N 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 238000002513 implantation Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000013077 target material Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 238000000427 thin-film deposition Methods 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/54—Controlling or regulating the coating process
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/34—Sputtering
- C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
Definitions
- This invention relates to the physical vapor deposition and, more particularly, to a method and apparatus for depositing onto substrates, particularly substrates formed of gallium arsenide, coatings, particularly refractory metal coatings, by physical vapor deposition.
- GaAs gallium arsenide
- device feature dimensions such as integrated circuit implant depth and gate width continue to decrease.
- deposition of refractory metals is typically employed.
- Conventional processes for depositing refractory metals have the potential of causing damage to GaAs substrates that adversely affects devices being formed thereon that have features having such decreased dimensions.
- Physical vapor deposition (PVD) has become recognized as a process useful to deposit refractory metals to form sub-micron sized features such as, for example, ohmic and Shottky contacts, on GaAs wafers.
- Certain stages of a PVD process can subject the surface of a GaAs substrate to damage.
- implanted n-type GaAs surfaces that are exposed directly to the plasma ignition stage in a DC magnetron PVD system can incur damage from impinging secondary electrons, from ions, and from reflected fast neutral atoms that are produced during plasma ignition.
- the damage caused by a DC magnetron sputter coating PVD process is approximately 10 "3 times that of typical plasma processing techniques such as reactive ion etching (RIE) and electron cyclotron resonance
- DC magnetron sputtering produces relatively low damage to GaAs substrates
- FETs field effect transistors
- Device parameters affected by the damage are FET gain, breakdown voltage, and transconductance. Typical of such damage is the implantation of ions and neutral atoms, the production of broken bonds or the formation of dangling bonds in the surface microstructure, and the changing of the density and type of surface states.
- the damage induced by DC magnetron PVD sputtering is self-limiting. For example, regardless of process time, within the first second of the process 75% of the total damage is completed and after two seconds, 100% of the damage has taken place. Due to the physics of DC magnetron PVD processing, the damage that it produces on GaAs substrates is believed to be localized to a region adjacent the surface (30 A to 60 A deep) of the GaAs implanted region. Nonetheless, the damage produced during plasma ignition is sufficient to materially reduce the quality and quantity of devices produced by PVD.
- a physical shutter is effective to reduce damage during plasma ignition, there are several disadvantages to using a physical or mechanical shutter in a manufacturing environment. For example, since a physical shutter is typically situated above the wafer, it receives a large amount of metal deposit. As it moves in a vacuum, it generates a significant number of particles, typically adding more than 500 particles of 0.5 microns or larger. As gate sizes decrease, high particle density increases the number of defective devices produced and thereby reduces device yield. Further, a physical shutter is prone to mechanical failures and requires preventive maintenance, both of which add to system downtime.
- a primary objective of the present invention is to provide a method and an apparatus by which substrates that are prone to damage during plasma ignition are protected from such damage without the need to shield such substrates with a physical shutter.
- a particular objective of the invention is to provide a method and apparatus for depositing refractory metals onto damage prone substrates, especially gallium arsenide substrates, by physical vapor deposition processes while minimizing the damage caused to the substrate surface.
- a further particular objective of the present invention is to generally eliminate the need for a physical shutter in PVD, especially in PVD of refractory metals onto GaAs substrates.
- the present invention achieves its objectives in part by controlling the parameters of a PVD system in such a way as to minimize the density of high energy particles created during plasma ignition from reaching the substrate.
- Such high energy particles are those particles having sufficient energy to damage a substrate such as GaAs wafer.
- the invention does so without the use of a mechanical or physical shutter.
- the invention incorporates a plasma ignition process sequence using a relatively high pressure gas burst in combination with the control of one or more other parameters of the system.
- the control of other parameters includes: (a) varying the plasma ignition gas composition, and (b) varying target-to-substrate distance, each to maximize the effectiveness and number of gas phase scattering events.
- the control of other parameters further includes: (c) increasing the magnetron magnetic field strength so as to capture a higher number of secondary electrons emitted from the sputter target, and (d) the use of a sputter target cleaning procedure to reduce the density of secondary electron emission.
- control of other parameters includes: (e) adjusting the power supply power ramping-up time to the target, and (f) the use of a circuit to drain charge build up on the floating GaAs substrate.
- a plurality, or more preferably a majority, of the steps of controlling other parameters is employed with the high pressure gas burst in the plasma ignition sequence. All of the other parameter controls may be used and optimized in order to minimize, without the use of a mechanical shutter, the density of particles reaching the GaAs substrate that are created during plasma ignition and that have sufficient energy to damage the GaAs wafer.
- the plasma ignition process sequence of the present invention as set forth herein is referred to as a "virtual shutter" and produces the desired function, traditionally achieved only by the use of a mechanical shutter, of prohibiting damage induced during the plasma ignition step of a DC magnetron PVD sputtering process on GaAs surfaces.
- the invention does so without the use of a physical or mechanical shutter and hence without the disadvantages of a physical shutter. Damage that would cause surface state changes due to secondary electron impingement is particularly avoided using the virtual shutter of the present invention.
- Fig. 1 is a graph comparing the effects of the various controlled parameters in the present invention.
- Fig. 2 is a graph illustrating the repeatability of data illustrated in Fig. 1.
- Fig. 3 is a graph similar to Fig. 1 comparing the effects of different controlled parameters.
- Fig. 4 is a graph similar to Fig. 3 illustrating the effects of the controlled parameter of target condition.
- Fig. 5 is a graph illustrating the relationship between target voltage and the number of conditioning runs.
- Fig. 6 is a graph similar to Fig. 4 illustrating the effects of a controlled parameter of substrate bias.
- Fig. 7 is a diagrammatic illustration of a sputter coating chamber embodying principles of the present invention. Detailed Description of the Preferred Embodiments
- the preferred embodiment of the present invention provides a virtual shutter for a physical vapor deposition (PVD) apparatus such as a sputter coating apparatus.
- PVD physical vapor deposition
- a sputter coating apparatus such as a sputter coating apparatus.
- PVD physical vapor deposition
- One such apparatus is described, for example in commonly assigned U.S. Patent No. 4,915,564, hereby expressly incorporated by reference herein.
- virtual shutter is meant a feature or combination of features that serve the purposes of a physical or mechanical shutter of a type commonly used in sputter coating or other PVD equipment to shield a substrate or other article from coating material deposition or bombardment by energy or particles during some phase of the operation of the apparatus, but which does so without the actual use of a physical or mechanical shutter.
- the virtual shutter of the present invention provides, in its preferred embodiment, a combination of hardware and process configurations having several components, including: (1) a plasma ignition gas burst sequence, and (2) parameter controls from among the following: (a) plasma ignition gas species selection, (b) DC magnetron magnet field strength variation, (c) target to substrate distance variation, (d) a sputter target conditioning procedure, (e) cathode power ramp control, and (f) control of substrate floating potential.
- Each component of the combination makes a contribution to the virtual shutter's function of prohibiting secondary electrons, reflected neutral atoms, and ions from striking the GaAs surface. Since secondary electron emission is dependant upon the sputter material, the optimum configuration of the virtual shutter depends on the sputter material being used and, accordingly, the configuration differs from sputter material to sputter material to maximize effectiveness of the virtual shutter.
- the plasma ignition gas burst sequence is a pre-deposition process designed to ignite a low damage plasma, comparable to a plasma ignition sequence with a mechanical shutter closed, and to prepare the chamber conditions to deposit thin films during the portion of the process comparable to that performed with a mechanical shutter open.
- the plasma ignition gas burst sequence uses either argon (Ar), krypton (Kr), xenon (Xe), or mixtures of fluorinated molecular gases with Ar, Kr, or Xe burst gas.
- a plasma ignition gas is released into the chamber to produce a relatively high pressure in the process chamber, for example, in the range of from 100 to 500 mTorr.
- the process time for this step is set to be sufficiently long enough to allow the gas to equilibrate or equalize throughout the chamber.
- plasma ignition takes place using low ignition power level of, for example, 50-200 Watts.
- the gas burst is terminated, and the process progresses to that portion referred to herein as the virtual shutter open portion of the process, with argon (Ar) process gas being introduced into the chamber for sputtering.
- Ar argon
- the plasma remains at the low ignition power level for a time sufficient to allow cathode voltage to stabilize.
- thin film deposition begins with the DC magnetron power increasing to the process power set point.
- the apparatus power supply is programmed to reach the set point in six seconds.
- the effect of the plasma ignition gas burst sequence is optimized by controlling other parameters such as the plasma ignition gas species used in the gas burst sequence. This may be varied depending upon the sputter material being deposited. For materials that were observed to cause higher levels of damage such as tungsten-titanium (WTi), xenon is preferred. Since the damage is much lower when sputtering titanium, argon is sufficient. For materials with high secondary electron emission coefficients, such as insulating materials or surfaces with a high carbon or oxygen content, mixtures of fluorinated molecules and noble gases are preferred. DC magnetron magnet field strength
- the effect of the plasma ignition gas burst sequence may be optimized by controlling other parameters such as DC magnetron magnet field strength where possible.
- DC magnetron magnet field strength where possible.
- the one that produces a higher field strength reduces plasma ignition phase damage to the substrate to a greater degree than one producing a weaker magnetron field.
- replacing a DC magnetron magnet pack producing a field strength of less than 300 Gauss with one producing a higher magnetic field strength of approximately 400 gauss for example, optimizes the function of the virtual shutter in its closed condition, reducing substrate damage during plasma ignition.
- magnet field strength is electrically controllable, such as with magnetrons using electromagnets or in systems where field strength is adjustable by moving permanent magnets, increasing field strength during the virtual shutter closed condition reduces substrate damage during plasma ignition.
- the effect of the plasma ignition gas burst sequence is optimized by controlling other parameters such as by providing an increased target-to- substrate distance.
- the distance variation that is desired is dependent upon the sputter material.
- the target-to-substrate distance may be set to a distance that is greater than would otherwise be required during the deposition process.
- the target to substrate distance is, during plasma ignition, more than twice the target-to-substrate distance during normal sputter deposition from the target onto the substrate.
- the distance is increased for plasma ignition from that used during PVD processing, and preferably it is more than doubled during plasma ignition.
- a conditioning sequence may be performed prior to plasma ignition and deposition, and is preferred whenever the system has been idle for any significant period of time, such as, for example, for more than 20 minutes where materials such as titanium or titanium-tungsten are being sputtered.
- a specific target conditioning example is described in the example below. It preferably includes using process wafers and sputtering parameters that mimic the deposition process.
- the DC magnetron cathode power used for this step is preferably the same as that used for the deposition test. During each process run, the cathode voltage is monitored, and the conditioning step is regarded as completed when the cathode target voltage is stabilized. For most materials, three to ten process steps stabilize the cathode voltage. Power Supply Ramp Time
- the effect of the plasma ignition gas burst sequence is optimized by controlling other parameters such as by controlling the ramp time of the target power supply over several seconds.
- a ramp time of at least about three seconds is preferable. Setting the power ramp time closer to at least about six seconds is, however, more desirable. Control of the Substrate Floating Potential
- the substrate floating potential is preferably controlled so as to be fixed.
- fixing the substrate potential at approximately -12 volts is preferable. This can be accomplished by using a 12 volt zener diode, with the cathode side of the diode connected to the system ground and the anode side of the diode attached to the substrate.
- GaAs substrates were prepared by implanting new GaAs wafers with silicon (Si), encapsulated with silicon nitride (Si 3 N 4 ), and the implant was activated using a rapid thermal anneal. After removing the Si 3 N 4 , the pre-deposition R s of the n-GaAs wafers was measured using a non-contact resistivity measurement system. The n-GaAs wafer was then used to test various plasma ignition and deposition sequences.
- Si silicon
- Si 3 N 4 silicon nitride
- the deposited metal was chemically etched and the post-deposition R s was measured.
- the change in R s was calculated by using the difference of the average post and predeposition values.
- the average value comprised fifty-four measurement points per wafer.
- the magnitude of the R s change is a strong indicator of FET device performance. Increasing changes in R s values correspond to higher levels of damage.
- the experimental procedure had about a 10 ohms per square error.
- Substrate Voltage 12 Volts 12 Volts The plasma ignition gas burst sequence is configured to mimic the functionality of a physical shutter. Although the components change to accommodate different sputter materials, the sequence remains substantially the same from sputter material to sputter material.
- the pre-plasma ignition high pressure step referred to is with the shutter when in the closed position.
- the shutter effectiveness is directly related to the scattering cross section, mean free path, and collision frequency of secondary electrons, atoms, and ions with the plasma ignition gas.
- Typical chamber pressures during the gas burst are between 160 and 250 mTorr. At these pressures, the mean free paths for atoms and ions are on the order of 10 "4 meters.
- the repeatability of the performance of the virtual shutter technique for depositing Ti using Ar as the process gas was tested by repeating the identical process over a one month period. During this time, the system underwent the normal preventive maintenance schedule, and several kilowatt hours of material were removed from the sputter target. This data was validated using electrical data from active devices. The results from the virtual shutter are very reproducible, as illustrated in Fig. 2. The variations at run numbers 6,7, 10, and 11 are due to variations in the chemical etch used for preparing the samples.
- the R s change for tungsten-titanium (WTi) deposition was found to be approximately 40% higher than for titanium (Ti) deposition when all of the parameter controls illustrated in Fig. 1 are used.
- the virtual shutter pressure and target-to-substrate spacing increase is sufficient to effectively scatter atoms and ions and eliminated the damage contribution when sputtering Ti. Accordingly, a sputter material dependance is observed in the process.
- One difference between sputter material that is believed to affect the effectiveness of the virtual shutter is the secondary electron emission coefficient. Experimental and theoretical data for secondary electron emission coefficients for Ti and W are shown in Table 2.
- the coefficient for W is 50% higher than that for Ti (emission per incident primary electron), while the theoretical coefficient for W is slightly lower than that for Ti (emission per incident ion).
- the theoretical values in Table 2 are rough estimates of the coefficient.
- the actual secondary emission coefficients are dependant upon surface conditions, alloy composition, contamination and morphology.
- the R s change and electrical data from n-GaAs substrates suggest that the WTi alloy has a higher secondary emission coefficient than Ti.
- a plasma ignition gas species of Xe is preferred.
- Xe facilitates plasma ignition due to its high polarizability and the low ionization potential when compared to other noble gases.
- the polarizability of Xe gas is 2.5 times the value for Ar gas, and the ionization potential is 3.629 eV lower than for Ar.
- the electron collision probability which is defined as the average number of collisions in a I cm path of gas at I Torr, for Xe is 3.3 times higher for Ar.
- Xe lowers the kinetic energy of the secondary electrons.
- the kinetic energy (KE) of a secondary electron (se) is dependant upon the ionization potential (IP) of the process gas.
- Improvements of the plasma ignition gas burst can be made by incorporating small amounts of fluorinated gas molecules with the noble gases used for plasma ignition. This will increase the contribution of electron polarization scattering, elastic and inelastic collisions, and promote electron-ion recombination. This is particularly useful for sputtering insulating material which typically has high secondary electron emission coefficients.
- the DC magnetron magnetic field is preferably increased.
- the magnetic field used in a magnetron application is often designed to confine and accelerate secondary electrons back into the plasma to maintain the discharge.
- a standard magnet pack configuration may have a field strength less than 300 Gauss.
- the R s change has been lowered, for example, from 52 to 40 ohms/sq, a 23% decrease, as illustrated in Fig. 1.
- the R s change is a strong function of sputter surface conditioning.
- the sputter target conditioning sequence reduces the R s change from 52 to an average of 25 ohms/sq.
- Secondary electron yield is sensitive to the sputter surface conditions. For example, contamination of the sputter surface with organic or oxide materials can increase the secondary electron emission coefficient by a factor of two to three.
- the conditioning sequence used is equivalent to the performance of a PVD sputtering process on several wafers prior to performing the actual coating of the GaAs substrates.
- the sputtering process cleans off contamination and oxides from the sputter material surface.
- Cathode voltage can be monitored to determine the cleanliness of the sputter material, as illustrated in Fig. 5. As the sputter material surface is cleaned, the cathode voltage decreases.
- the conditioning sputter sequence characterizes the impedance of the process chamber and provides a chamber quality baseline for future testing and processing.
- the substrate is frequently electrically floating. During the plasma ignition, the substrate takes on a positive potential, and becomes slightly negative after the plasma stabilizes. To reduce the range of substrate potential while keeping the electrically floating characteristic, a 12 volt zener diode may be attached to the substrate, with the cathode side of the diode connected to system ground and with the anode side attached to the substrate. With the zener diode, the substrate is fixed at, for example, -12 volts during the plasma ignition and process. Any charge build up due to particle impingement passes
- the preferred embodiment of the invention is one where all of the components or other control parameters referred to above are employed to lower the damage to an electrically undetectable level on a n-GaAs surface.
- the mechanism for damage to a GaAs surface and degradation of FET device parameters is believed to be largely due to secondary electrons striking the n-GaAs surface and changing the density and type of surface states.
- the n-GaAs surface might have a high number of donor states. It is believed that during the PVD process, the surface is bombarded with secondary electrons and these states become neutralized, thus lowering the FET performance. This is intended only to be a theoretical view of the mechanism, and the scope of the invention which is not intended to be limited by the theory involved.
- Fig. 7 illustrates a sputter coating apparatus 10 in which the method of
- the invention may be performed. It includes a vacuum processing chamber 11 having a gas inlet control 12 through which any one of a variety of gases may be introduced into the chamber 11.
- the source 12 may include a source 13 of argon to be used for sputtering and a source 14 of xenon to be used for plasma ignition.
- a controller 15 is provided, which may be programmed to cause the filling of the chamber 11 with xenon from source 14 during plasma ignition and then to evacuate the xenon while pumping the chamber 11 to a lower pressure by a vacuum pump 16 and a filling of the chamber 11 at this lower pressure with argon from the source 13 during sputter coating.
- the chamber 11 has a substrate support or holder 20 at one end thereof fixed to the top of a moveable mount 21 which can be raised and lowered by an elevator 22 under the control of the controller 15.
- a sputtering cathode assembly 24 having a sputtering target 24 supported thereon which faces a substrate 27, of for example GaAs, on the support 20.
- the elevator 22 may be controlled by the controller 15 so that the mount 21 may be lowered during plasma ignition to increase its distance from the target 24 and raised to bring the substrate 27 closer to the target 24 during deposition.
- a power supply 30 is connected to the cathode 25 to energize the target 24 for sputter processing of the substrate 27.
- the power supply 30 is preferably controlled by the controller 15 such that the power to the target is low during plasma ignition and is gradually increased over a period of about four to eight seconds to the power level used for sputtering.
- a magnetron magnet assembly 40 is included in the cathode assembly 25 which is configured to produce a relatively strong magnetic field in the chamber 11 during plasma ignition.
- This magnet may be of variable field strength, such as an electromagnet or moveable permanent magnet, that is controlled by the controller 15 in a way that increases field strength during plasma ignition. Alternatively, a separate magnet may be provided to increase field strength during plasma ignition. If variable magnets are not practical, the magnetron magnet should be selected which provides a stronger than average field.
- a voltage limiting circuit 45 is also provided between the substrate support 20 and the chamber ground in order to limit the potential on the substrate 27 during plasma ignition.
- This circuit 45 may include a zener diode 46 or other components or controls to prevent high substrate potential from developing during plasma ignition.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physical Vapour Deposition (AREA)
- Electrodes Of Semiconductors (AREA)
- Physical Deposition Of Substances That Are Components Of Semiconductor Devices (AREA)
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP00942703A EP1194608B1 (en) | 1999-06-22 | 2000-06-08 | Sputtering method using virtual shutter |
JP2001505361A JP3798316B2 (en) | 1999-06-22 | 2000-06-08 | Sputtering method using virtual shutter |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/337,574 | 1999-06-22 | ||
US09/337,574 US6156164A (en) | 1999-06-22 | 1999-06-22 | Virtual shutter method and apparatus for preventing damage to gallium arsenide substrates during processing |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2000079018A1 true WO2000079018A1 (en) | 2000-12-28 |
Family
ID=23321087
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2000/015715 WO2000079018A1 (en) | 1999-06-22 | 2000-06-08 | Sputtering method using virtual shutter |
Country Status (6)
Country | Link |
---|---|
US (1) | US6156164A (en) |
EP (1) | EP1194608B1 (en) |
JP (1) | JP3798316B2 (en) |
KR (1) | KR100700811B1 (en) |
TW (1) | TW539756B (en) |
WO (1) | WO2000079018A1 (en) |
Families Citing this family (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR20010024504A (en) * | 1997-10-15 | 2001-03-26 | 히가시 데쓰로 | Apparatus and method for adjusting density distribution of a plasma |
US6461483B1 (en) * | 2000-03-10 | 2002-10-08 | Applied Materials, Inc. | Method and apparatus for performing high pressure physical vapor deposition |
TW512180B (en) * | 2000-09-21 | 2002-12-01 | Promos Technologies Inc | Method for maintaining the cleanness of a vacuum chamber of physical vapor deposition system |
KR100399019B1 (en) * | 2001-04-23 | 2003-09-19 | 한국과학기술연구원 | Chemical Vapor Deposition System at Ambient Temperature And The Preparation Method for Metal Composite Film Using The Same |
US6946054B2 (en) | 2002-02-22 | 2005-09-20 | Tokyo Electron Limited | Modified transfer function deposition baffles and high density plasma ignition therewith in semiconductor processing |
NL1026532C2 (en) * | 2004-06-30 | 2006-01-02 | Tno | Method and means for generating a plasma at atmospheric pressure. |
US8795486B2 (en) * | 2005-09-26 | 2014-08-05 | Taiwan Semiconductor Manufacturing Company, Ltd. | PVD target with end of service life detection capability |
SE536285C2 (en) * | 2011-04-07 | 2013-07-30 | Ionautics Ab | Sputtering process for sputtering a target of carbon |
CN103132032A (en) * | 2013-03-15 | 2013-06-05 | 上海和辉光电有限公司 | Sputtering equipment for reducing indium tin oxide (ITO) sputtering damage substrate and method thereof |
US10886104B2 (en) | 2019-06-10 | 2021-01-05 | Advanced Energy Industries, Inc. | Adaptive plasma ignition |
CN112210763B (en) * | 2019-07-11 | 2022-05-24 | 联芯集成电路制造(厦门)有限公司 | Method for depositing a metal layer on a wafer |
US11688584B2 (en) | 2020-04-29 | 2023-06-27 | Advanced Energy Industries, Inc. | Programmable ignition profiles for enhanced plasma ignition |
CN116200707A (en) * | 2023-05-04 | 2023-06-02 | 粤芯半导体技术股份有限公司 | Preparation method of semiconductor cobalt silicide film layer |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4500408A (en) * | 1983-07-19 | 1985-02-19 | Varian Associates, Inc. | Apparatus for and method of controlling sputter coating |
JPH0718437A (en) * | 1993-07-05 | 1995-01-20 | Anelva Corp | Formation of thin film by bias sputtering |
EP0665306A1 (en) * | 1994-01-19 | 1995-08-02 | TOKYO ELECTRON AMERICA Inc. | Apparatus and method for igniting plasma in a process module |
US5494699A (en) * | 1993-12-14 | 1996-02-27 | Goldstar Electron Co., Ltd. | Method for the fabrication of electroluminescence device |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4915564A (en) * | 1986-04-04 | 1990-04-10 | Materials Research Corporation | Method and apparatus for handling and processing wafer-like materials |
AU8629491A (en) * | 1990-08-30 | 1992-03-30 | Materials Research Corporation | Pretextured cathode sputtering target and method of preparation thereof and sputtering therewith |
TW271490B (en) * | 1993-05-05 | 1996-03-01 | Varian Associates | |
DE69506619T2 (en) * | 1994-06-02 | 1999-07-15 | Applied Materials Inc | Inductively coupled plasma reactor with an electrode to facilitate plasma ignition |
US5667645A (en) * | 1996-06-28 | 1997-09-16 | Micron Technology, Inc. | Method of sputter deposition |
US5830330A (en) * | 1997-05-22 | 1998-11-03 | Tokyo Electron Limited | Method and apparatus for low pressure sputtering |
US5976334A (en) * | 1997-11-25 | 1999-11-02 | Applied Materials, Inc. | Reliable sustained self-sputtering |
-
1999
- 1999-06-22 US US09/337,574 patent/US6156164A/en not_active Expired - Lifetime
-
2000
- 2000-06-08 JP JP2001505361A patent/JP3798316B2/en not_active Expired - Lifetime
- 2000-06-08 KR KR1020017016348A patent/KR100700811B1/en active IP Right Grant
- 2000-06-08 WO PCT/US2000/015715 patent/WO2000079018A1/en active IP Right Grant
- 2000-06-08 EP EP00942703A patent/EP1194608B1/en not_active Expired - Lifetime
- 2000-06-20 TW TW089112075A patent/TW539756B/en not_active IP Right Cessation
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4500408A (en) * | 1983-07-19 | 1985-02-19 | Varian Associates, Inc. | Apparatus for and method of controlling sputter coating |
JPH0718437A (en) * | 1993-07-05 | 1995-01-20 | Anelva Corp | Formation of thin film by bias sputtering |
US5494699A (en) * | 1993-12-14 | 1996-02-27 | Goldstar Electron Co., Ltd. | Method for the fabrication of electroluminescence device |
EP0665306A1 (en) * | 1994-01-19 | 1995-08-02 | TOKYO ELECTRON AMERICA Inc. | Apparatus and method for igniting plasma in a process module |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 1995, no. 04 31 May 1995 (1995-05-31) * |
Also Published As
Publication number | Publication date |
---|---|
TW539756B (en) | 2003-07-01 |
KR20020010722A (en) | 2002-02-04 |
EP1194608A1 (en) | 2002-04-10 |
KR100700811B1 (en) | 2007-03-27 |
JP2003517517A (en) | 2003-05-27 |
US6156164A (en) | 2000-12-05 |
JP3798316B2 (en) | 2006-07-19 |
EP1194608B1 (en) | 2011-12-28 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4874494A (en) | Semiconductor manufacturing apparatus | |
US7884032B2 (en) | Thin film deposition | |
US6156164A (en) | Virtual shutter method and apparatus for preventing damage to gallium arsenide substrates during processing | |
KR100372385B1 (en) | Thin film fabrication method and thin film fabrication apparatus | |
US6051114A (en) | Use of pulsed-DC wafer bias for filling vias/trenches with metal in HDP physical vapor deposition | |
US6323124B1 (en) | Resputtering to achieve better step coverage | |
US6673716B1 (en) | Control of the deposition temperature to reduce the via and contact resistance of Ti and TiN deposited using ionized PVD techniques | |
KR100677718B1 (en) | Sputtering chamber shield promoting reliable plasma ignition | |
US6652718B1 (en) | Use of RF biased ESC to influence the film properties of Ti and TiN | |
US20070012558A1 (en) | Magnetron sputtering system for large-area substrates | |
EP0859070B1 (en) | Coating of inside of vacuum chambers | |
JP2008504687A (en) | Etching and deposition control for plasma implantation | |
JPH113878A (en) | Method and device for controlling surface condition of ceramic substrate | |
KR20210130264A (en) | Method and apparatus for deposition of multilayer devices with superconducting films | |
US6413384B1 (en) | Method for maintaining the cleanness of a vacuum chamber of a physical vapor deposition system | |
KR20190002332A (en) | Plasma processing method and plasma processing apparatus | |
KR20210130261A (en) | Method and apparatus for deposition of metal nitrides | |
Bass et al. | Effects of substrate preparation on the stress of Nb thin films | |
JPS63501432A (en) | Sputtering method for reducing bulges in an aluminum layer formed on a substrate | |
US11222785B2 (en) | Method for depositing a metal layer on a wafer | |
CN115874154B (en) | Semiconductor structure, chip, application thereof and film deposition method | |
US20230282451A1 (en) | Cover ring to mitigate carbon contamination in plasma doping chamber | |
Shin et al. | Suppression of topography dependent charging using a phase-controlled pulsed inductively coupled plasma | |
KR20070032342A (en) | Etch and deposition control for plasma implantation |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): JP KR |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
DFPE | Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101) | ||
WWE | Wipo information: entry into national phase |
Ref document number: 1020017016348 Country of ref document: KR |
|
ENP | Entry into the national phase |
Ref country code: JP Ref document number: 2001 505361 Kind code of ref document: A Format of ref document f/p: F |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2000942703 Country of ref document: EP |
|
WWP | Wipo information: published in national office |
Ref document number: 1020017016348 Country of ref document: KR |
|
WWP | Wipo information: published in national office |
Ref document number: 2000942703 Country of ref document: EP |
|
WWG | Wipo information: grant in national office |
Ref document number: 1020017016348 Country of ref document: KR |